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Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/12/2014 Publication Date: 10/11/2014 Citation: Dogramaci, M., Horvath, D.P., Anderson, J.V. 2014. Dehydration-induced endodormancy in crown buds of leafy spurge highlights involvement of MAF3- and RVE1-like homologs, and hormone signaling cross-talk. Plant Molecular Biology. 86(4):409-424. DOI: 10.1007/s11103-014-0237-2. Interpretive Summary: Persistence of invasive perennial weeds such as leafy spurge involves their ability to vegetatively regenerate new shoot growth from underground adventitious buds (UABs) following periods of environmental stress. Induction of endodormancy in these reproductive buds allows them to survive in the soil until environmental conditions are favorable for regeneration of new shoots. Thus, identifying the molecular mechanisms involved in endodormancy induction could provide insights for managing invasive weedy species. In this study, we concluded that exposure of leafy spurge plants to 7-14 days of dehydration induces endodormancy in UABs. Analysis of gene expression data from this study, in combination with previous studies, helped identify potential molecular markers (HY5, MAF3, RVE1, and RD22) specific to endodormancy induction in UABs. The results of this study were further used to propose several hypothetical models for regulation of endodormancy in UABs of leafy spurge. These models include the interaction of MAF3 with other gene products involved in regulating vegetative growth, and hormone-dependent regulation of the circadian clock output gene RVE1 involved in regulating downstream expression of stress-responsive genes. These pathways and markers may serve as new targets for manipulating vegetative production that reduce economic costs to land managers worldwide. Technical Abstract: Vegetative shoot growth from underground adventitious buds of leafy spurge is critical for survival of this invasive perennial weed after episodes of severe abiotic stress. To determine the impact that dehydration-stress has on molecular mechanisms associated with vegetative reproduction of leafy spurge, greenhouse plants were exposed to mild- (3-day), intermediate- (7-day), severe- (14-day) and extended- (21-day) dehydration treatments. Aerial tissue of treated plants was then decapitated and soil was rehydrated to determine the growth potential of underground adventitious buds. Compared to well-watered control plants, mild-dehydration accelerated new vegetative shoot growth but intermediate- and severe-dehydration treatments both delayed and reduced shoot growth; 21-day dehydration treatment inhibited initiation of new vegetative shoots and was considered a lethal treatment. Overall, transcriptome profiles revealed that 2109 genes were differentially-expressed (P<0.05) in crown buds in response to the various dehydration treatments. Sub-network enrichment analyses identified central hubs of over-represented genes involved in processes such as hormone signaling (i.e., ABA, auxin, ethylene, GA, and JA), response to abiotic stress (DREB1A/2A, RD22) and light (PIF3), phosphorylation (MPK4/6), gene silencing (miRNA172a), circadian regulation (CRY2, PHYA), and flowering (AGL20, AP2, FLC). Further, results from this and previous studies highlight HY5, MAF3, MYB-like/RVE1 and RD22 as molecular markers for endodormancy in crown buds of leafy spurge. Early response to dehydration also highlighted involvement of upstream ethylene and jasmonate signaling, whereas extended dehydration impacted ABA signaling. The identification of conserved ABRE- and MYC-consensus, cis-acting elements in the promoter of a leafy spurge gene similar to Arabidopsis RVE1 (AT5G17300) implicates a potential role for ABA signaling in its dehydration-induced expression. Response of these molecular mechanisms to dehydration-stress provides insights on the ability of invasive perennial weeds to adapt and survive under harsh environments, which will be beneficial for addressing future management practices. |
